In conventional panoramic night vision systems two separate monocular subassemblies are provided. Each monocular subassembly includes two image channels. Each of the image channels may be provided by an objective assembly that transmits an image from a viewed object to an image intensifier tube that intensifies the luminance of the image, and outputs the intensified image to another optical assembly, such as an eye piece.
The panoramic effect of such a night vision system is achieved by angling the optical axes of each of the two image channels of each monocular relative to one another, but having partially overlapping fields of view. The separate image channels must be combined, such as by an eyepiece, to provide a wide angle field of view. In order to provide the desired panoramic view, it is necessary that the individual optical axes of the image channels be properly aligned with the image combiner. If the optical axes of the separate image channels are not properly aligned, the image may be sheared.
Unfortunately, the center of the optical axis of an image intensifier tube may vary between different image intensifier tubes. The variation in the optical center of image intensifier tubes must be accommodated during the manufacture or assembly of a panoramic night vision system in order to assure the proper alignment of the optical axis of each channel in a monocular. Conventionally, during manufacture of the night vision system the optical center of the image intensifier tube is properly aligned with the optical axis of the assembly and the image intensifier tube is secured in place in the optical assembly to prevent shifting of image intensifier tube. Securing the image intensifier tube in the optical assembly may include bonding the image intensifier tube to an adjacent component of the assembly, clamping the image intensifier tube in an axial manner using a retaining ring, etc.
While the above techniques may be able to overcome the problem of initial alignment of the image intensifier tube in the night vision system, optical tolerances are too high to allow replacement or removal of the image intensifier tube without realigning and re-securing image intensifier tube.
Accordingly, there is a need for a night vision system and method that allows self-alignment of an image intensifier tube upon replacement of the tube.